Blob at the start of object when using spiral mode

Bambu Lab Software
1

Hi all,

I have a curious problem. When I use spiral mode to print an object, the printer always starts the object by extruding a big blob of filament. Can anybody tell me why this is happening? Does anyone experience the same thing?

20231004_134016
20231004_1340161920×1440 423 KB

I have resorted to using a raft, so that the blob is not at the start of the object but at the start of the raft. But the raft leaves my object with a rough bottom edge, which is undesired. Any help or suggestions are very welcome :slight_smile:

2

A skirt may be more appropriate than a raft as it is not attached to your model.

3

I figured the same, so I tried it with a skirt, doesn’t fix the problem unfortunately. It looks as though Studio is adding a priming action, like a ‘Retraction Extra Prime Amount’ in Cura. :confused:

Schermafbeelding 2023-10-04 142103

I use 0 bottom layers by the way.

4

When I check the ‘Unretract’ option in the legenda, a massive light blue dot appears right at the spot where the blob is deposited. When I look at the g-code I see this:

; start printing object, unique label id: XXX
M624 AQAAAAAAAAA=
G1 Z0.120
G1 E.8 F1800   <==== Unretraction
M204 S5000

You can see Studio inserts an 0.8mm extrusion, which is way to much.
The default retraction distance is 0.8mm so I guess Studio uses the same value for the unretraction. But since there hasn’t been a previous retraction an untretraction seems unnecessary?

5

What filament are you printing and at what temperature? I’ve seen blobs like that when I printed the material too hot.

4 Likes
6

This is Bambu PLA Silk on the recommended temperature. But the blob is always there regardless of filament type/brand and temperature. The blob is something that Studio causes by inserting a too large unretraction.

I’m just wondering if anybody else ran into this problem or that it is just me. Maybe the 0 bottom layers is causing it?